The game is divided into two "volumes," each centering around a different main character and their friends. The first volume tells the story of Toxa Classico and the second volume is about Lacryma Christi. While each volume tells a complete story, the storylines intertwine in one major plot.

Each "chapter" of both volumes revolves around phantoms, beings which can be summoned by certain humans using "Kartia", magical cards which create whatever is written on them, such as Fire or Water. The player must summon and control phantoms to fight for him/her, as well as managing Kartia supplies, casting magic with Kartia and creating weapons for the human combatants. Kartia cards can be combined to create more powerful spells or phantoms. While phantoms may die during battle, if a human party member dies, the game ends and the chapter must be restarted.